US11002948B2ActiveUtilityA1

Zoom lens, optical apparatus and method for manufacturing the zoom lens

Assignee: NIKON CORPPriority: Dec 9, 2015Filed: Dec 9, 2016Granted: May 11, 2021

Est. expiryDec 9, 2035(~9.4 yrs left)· nominal 20-yr term from priority

Inventors:Keigo Koida

G02B 15/144511G02B 27/0025G02B 15/20G02B 13/02G02B 13/04G02B 27/646G02B 15/177

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References

Claims

Abstract

A zoom lens comprises, in order from an object, a first lens group (G 1 ) having negative refractive power, a second lens group (G 2 ) having positive refractive power, a third lens group (G 3 ) having negative refractive power, and a fourth lens group (G 4 ) having positive refractive power to satisfy the following conditional expression: 1.60<(− f 1)/ fw <2.50 where, f 1 denotes a focal length of the first lens group; and fw denotes a focal length of the zoom lens as a whole in a wide-angle end state.

Claims

exact text as granted — not AI-modified

The invention claimed is: 
     
       1. A zoom lens, comprising: in order from an object, a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power,
 the following conditional expressions being satisfied:
   1.60&lt;(− f 1)/ fw&lt; 2.50
 
   2.40&lt;( −f 3)/ fw≤ 4.034 
   45.0&lt;ω w&lt; 65.0
 
   15.0&lt;ω t&lt; 36.0
 
 
 where f 1  denotes a focal length of the first lens group, 
 fw denotes a focal length of the zoom lens as a whole in a wide-angle end state, 
 f 3  denotes a focal lenght of the third lens group, 
 ωw denotes a half angle of view (unit: degree) of the zoom lens as a whole in the wide-angle end state, and 
 ωt denotes a half angle view (unit: degree) of the zoom lens as a whole in a telephoto end state. 
 
     
     
       2. The zoom lens according to  claim 1 , wherein the first lens group comprises four lenses. 
     
     
       3. The zoom lens according to  claim 1 , wherein at least part of the third lens group moves in an optical axis direction upon focusing. 
     
     
       4. The zoom lens according to  claim 1 , wherein at least part of the first to the fourth lens groups comprises a vibration-proof lens group having a displacement component in a direction perpendicular to an optical axis. 
     
     
       5. The zoom lens according to  claim 1 , satisfying the following conditional expression:
   1.00&lt;( TLw−TLt )/ fw    
 where TLw denotes an optical total length of the zoom lens in the wide-angle end state, and 
 TLt denotes an optical total length of the zoom lens in a telephoto end state. 
 
     
     
       6. The zoom lens according to  claim 1 , satisfying the following conditional expression:
   0.60&lt;( ft/fw )/((− f 1)×β34 t )&lt;1.00
 
 where ft denotes a focal length of the zoom lens as a whole in a telephoto end state, and 
 β 34   t  denotes a composite magnification of the third lens group and the fourth lens group in the telephoto end state. 
 
     
     
       7. The zoom lens according to  claim 1 , satisfying the following conditional expression:
   1.20&lt; f 3/ f 1&lt;3.00 
 where f 3  denotes a focal length of the third lens group. 
 
     
     
       8. The zoom lens according to  claim 1 , wherein the third lens group consists of one negative lens. 
     
     
       9. The zoom lens according to  claim 1 , wherein the fourth lens group consists of one positive lens. 
     
     
       10. The zoom lens according to  claim 1 , wherein the second lens group comprises, in order from an object, a positive lens, and a cemented lens formed of a positive lens and a negative lens. 
     
     
       11. The zoom lens according to  claim 1 , comprising an aperture stop between the first lens group and the second lens group. 
     
     
       12. The zoom lens according to  claim 1 , comprising an aperture stop between the first lens group and the third lens group, wherein, upon zooming, a distance between the aperture stop and a lens adjacent thereto changes. 
     
     
       13. The zoom lens according to  claim 1 , wherein at least two lens surfaces in the first lens group are aspherical. 
     
     
       14. The zoom lens according to  claim 1 , wherein, upon zooming, a distance between each lens group and a lens group adjacent thereto changes. 
     
     
       15. An optical apparatus, comprising the zoom lens according to  claim 1 . 
     
     
       16. A method for manufacturing a zoom lens which comprises: in order from an object, a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power,
 the method comprising a step of arranging the first to the fourth lens groups in a lens barrel so as to satisfy the following conditional expressions:
   1.60&lt;(− f 1)/ fw&lt; 2.50
 
   2.40&lt;(− f 3)/ fw≤ 4.034
 
   45.0&lt;ω w&lt; 65.0
 
   15.0&lt;ω t&lt; 36.0
 
 
 where f 1  denotes a focal length of the first lens group, 
 fw denotes a focal length of the zoom lens as a whole in a wide-angle state, 
 f 3  denotes a focal length of the third lens group, 
 ωw denotes a half angle of view (unit: degree) of the zoom lens as a whole in the wide-angle end state, and 
 ωt denotes a half angle view (unit: degree) of the zoom lens as a whole in a telephoto end state.

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